I think what he was getting at is that they are "not as effective" in teaching people how to build web applications. There are people who can learn this way, but for beginners, it is really difficult.
In terms of data, we have tried them all. Not just Treehouse and Codecademy, but the web apps already out on the market (in-browser tutorials, ebooks, screencasts, physical books, etc.). And a lot of the students we have in Code Academy have tried them as well. They told us they wanted something more than just doing these online tutorials by themselves. They wanted a learning environment where they could learn with other people who are passionate about learning web development, get instruction from a professional software developer, and have mentors who can help them with the learning.